I am not sure of Dr Markov is measuring LPS endotoxin in the urine. He takes warm urine samples in order to culture the bacteria that live in the kidneys.
Could be. I just found
this paper which says lipopolysaccharide (LPS) plays an important role in the pathogenesis of nonalcoholic fatty liver disease (NAFLD).
The info that Martin posted above says the liver filters 95% to 99% of LPS in the blood running through the hepatic portal system. So you can still get LPS entering the bloodstream from the intestines, because it is not filtered 100%.
It is mainly the digestive organs whose blood supply is filtered by the hepatic portal system (including pancreas and gallbladder). Spleen also. This filtering helps protect you from toxins if you have eaten something poisonous.
That is right.
I would like to know how often it is that you get a urinary tract infection from bacteria in the gut.
This study suggests that gut bacteria can indeed jump into the urinary tract and cause infections.
As explained just above, the immune priming theory of ME/CFS if true would suggest ME/CFS is only caused when there are multiple factors present. So a viral infection alone may not cause ME/CFS; but if you catch a viral infection while already having a kidney infection, these two factors together may trigger ME/CFS, as a result of immune priming.
The idea that it requires two or more simultaneous factors to be present before ME/CFS is triggered was first proposed by Erik Johnson. He proposed that in the 1984 Lake Tahoe ME/CFS outbreak, it required the presence of mold (or similar biotoxins) and a virus to trigger ME/CFS. See
this post.